Triboelectric charging vs charging by conduction

[versine]

Why does rubbing two objects together produce a different result than having them contact?

 

[anuttarasammyak]

Though in Japanese animation in https://www.achilles.jp/product/electronics/knowledge/static-electricity/
Explains peeling charges.

 

[sophiecentaur]

Why does rubbing two objects together produce a different result than having them contact?

I think there are to things at work here. Firstly, transferring charge requires Work to be done. In this case, it's actual mechanical work. Bringing two objects together involves less work than rubbing them together. Also, two objects, even described as flat are not actually flat; there will be very few touching points on a microscopic scale. Just bringing them together will, perhaps cause some small amount of charge transfer across those small areas. Rubbing will increase the total contact area over time and physical distortion (= work) of the surfaces will also cause charge transfer.